Magnetostrictive devices and systems

ABSTRACT

The device generates electrical energy from mechanical motion. The device includes at least one magnetostrictive element and at least one force modifier. The force modifier is coupled to the magnetostrictive element. The force modifier receives an input force and applies a modified force to the magnetostrictive element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/764,732, filed on Feb. 14, 2013, and U.S. Provisional Application No.61/809,155, filed on Apr. 5, 2013. Each of these applications isincorporated by reference herein in its entirety.

BACKGROUND

Many different systems exist for power generation. With advances intechnology comes the need to provide power to operate that technology.Frequently, power generation must be portable or able to collect energyfrom diverse environments without doing damage to that environment. Manyconventional systems are restricted in where and how they may bedeployed and also rely on wasteful, harmful, or unsustainable processes.

SUMMARY

Embodiments of a device are described. In one embodiment, the device isa device for generating electrical energy from mechanical motion. Anembodiment of the device includes at least one magnetostrictive elementand at least one force modifier. The force modifier is coupled to themagnetostrictive element. The force modifier receives an input force andapplies a modified force to the magnetostrictive element. Otherembodiments of the device are also described.

Embodiments of a method are also described. In one embodiment, themethod is a method for generating electrical energy from mechanicalmotion. In one embodiment, the method includes receiving an input forcefrom a mechanical motion. The method also includes modifying the inputforce. The method also includes applying a modified output to amagnetostrictive element. Other embodiments of the method are alsodescribed.

Embodiments of an apparatus are also described. In one embodiment, theapparatus is a buoy apparatus for generating electrical energy frommotion of ocean waves. The apparatus includes a buoy housing, amagnetostrictive element, a tether coupling point, a force modifier, anda coil. The magnetostrictive element is disposed within an interior ofthe buoy housing. The force modifier is disposed at least partiallywithin the interior of the buoy housing. The force modifier is coupledto the tether coupling point. The force modifier receives an input forcefrom the tether coupling point. The force modifier applies a modifiedoutput force to the magnetostrictive element. The coil is disposedwithin a magnetic field of the magnetostrictive element.

Other aspects and advantages of embodiments of the present inventionwill become apparent from the following detailed description, taken inconjunction with the accompanying drawings, illustrated by way ofexample of the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts one embodiment of a buoy-housed system with acontinuation of the tether inside the buoy.

FIG. 2 depicts one embodiment of a buoy-housed system with an upper loadplate.

FIG. 3( a) depicts a schematic diagram of one embodiment of a buoyapparatus for power generation.

FIG. 3( b) depicts a schematic diagram of another embodiment of a buoyapparatus for power generation.

FIG. 4( a) depicts a schematic diagram of one embodiment of a hydraulicforce modifier.

FIG. 4( b) depicts another embodiment of the hydraulic force modifier ofFIG. 4( a).

DETAILED DESCRIPTION

It will be readily understood that the components of the embodiments asgenerally described herein and illustrated in the appended figures couldbe arranged and designed in a wide variety of different configurations.Thus, the following more detailed description of various embodiments, asrepresented in the figures, is not intended to limit the scope of thepresent disclosure, but is merely representative of various embodiments.While the various aspects of the embodiments are presented in drawings,the drawings are not necessarily drawn to scale unless specificallyindicated.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by this detailed description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

Reference throughout this specification to features, advantages, orsimilar language does not imply that all of the features and advantagesthat may be realized with the present invention should be or are in anysingle embodiment of the invention. Rather, language referring to thefeatures and advantages is understood to mean that a specific feature,advantage, or characteristic described in connection with an embodimentis included in at least one embodiment of the present invention. Thus,discussions of the features and advantages, and similar language,throughout this specification may, but do not necessarily, refer to thesame embodiment.

Furthermore, the described features, advantages, and characteristics ofthe invention may be combined in any suitable manner in one or moreembodiments. One skilled in the relevant art will recognize, in light ofthe description herein, that the invention can be practiced without oneor more of the specific features or advantages of a particularembodiment. In other instances, additional features and advantages maybe recognized in certain embodiments that may not be present in allembodiments of the invention.

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the indicatedembodiment is included in at least one embodiment of the presentinvention. Thus, the phrases “in one embodiment,” “in an embodiment,”and similar language throughout this specification may, but do notnecessarily, all refer to the same embodiment.

Although many embodiments are described herein, at least someembodiments use mechanical force to cause stress in a magnetostrictiveelement, which results in changes in the magnetic properties and,thereby, induces a voltage in a coil surrounding the element.Embodiments described herein are different from conventional devices.

The power density of magnetostrictive power generation systems can beenhanced by the incorporation of systems that impart mechanicaladvantage. This may take the form of mechanical load amplification orapplied frequency amplification or both.

In some embodiments, a magnetostrictive energy harvester may be coupledwith one or more mechanical (e.g. levers, pulleys, block and tacklesystems) or hydraulic components/systems that can impart an enhancementin the mechanical load applied to the system.

In a hydraulic load enhancement system, an applied force imparted ontothe energy generation device/system from the environment may cause apiston to compress a fluid (e.g. hydraulic oil). The energy stored inthe pressurized fluid can then be used to apply stress to themagnetostrictive elements housed in the buoy. The use of hydraulics cancreate advantages in the harvesting of energy from this system. Theforce on the tethers causes a piston to compress a fluid such ashydraulic oil. The energy stored in the pressurized fluid can then beused to apply stress to the magnetostrictive elements. In someembodiments, the hydraulic energy would be to move a piston of adifferent bore size to obtain a force amplification/reduction whichcould be applied to the magnetostrictive elements. This could beadvantageous for power production, as a greater force multiplicationwill enhance the effective power density of the system. In someembodiments, such a system could be used to implement a way to preventextreme loads caused by large waves to be applied to the system. Thiscould be done by using a valve to release the pressure over a certainvalue. In some embodiments, a double acting hydraulic cylinder such thatthe system is compressing the fluid on a tensile and compressive appliedload. Another proposed use of the hydraulics would be a double actinghydraulic cylinder such that the system is compressing the fluid on bothsides of the wave.

In one embodiment it is possible to achieve higher energy density for anenergy generating device by increasing the frequency at which a stressis applied and released to the energy generating device. This can beaccomplished by using a hydraulic system that is properly configured aspart of the load transfer mechanism. In this case the energy or forcethat is the natural source from which electrical energy is beinggenerated is first transferred to a hydraulic component, typically ahydraulic cylinder. The hydraulic cylinder absorbs the energy from thesystem and stores it in a hydraulic accumulator. The stored energy fromthe accumulator is then transferred to the energy generator and isreleased in short pulses through the use of a series of valves and atiming mechanism. By converting a single large impulse of energy intomany discreet pulses of energy that are being applied to the energygenerator, in effect, a frequency amplification of the applied load tothe magnetostrictive material is accomplished.

Many conventional devices and systems to make electric power from oceanwaves have a design that included magnetostrictive power takeoff (PTO)units disposed along at least one tether between a buoy and an anchor.However, there are a number of difficulties associated with housingmagnetostrictive power take-off units inside individual waterproof,pressure-tight enclosures disposed along the taut tether connecting thebuoy to the mooring. These difficulties include transferring substantialloads through several watertight connection points, electricallyconnecting the PTOs, deployment, maintenance, corrosion protection ofindividual units, etc.

This invention relates to a buoy/mooring system with magnetostrictiveenergy harvesters disposed inside the buoy or a single bottom-foundedenclosure. These two embodiments have a number of advantages overindividual PTOs deployed along the tether, but there are also specificchallenges associated with each new embodiment. Some of the advantagesare:

-   -   1. Ease of maintenance    -   2. Less complicated corrosion protection    -   3. Use of fewer underwater electrical connections    -   4. No pressure vessel requirements (for buoy-housed system)    -   5. Ease of monitoring for failure (i.e. FMEA controls)    -   6. No loss of PTO in case of tether failure    -   7. Ease of deployment    -   8. Possible ability to amplify force (pulley/block-and-tackle        system)    -   9. Single flexible portion to accommodate motion (large        diaphragm)    -   10. More easily recoverable in case of catastrophic failure,        with the exception of sinking

FIG. 1 depicts one embodiment of a buoy-housed system 100 with acontinuation of the tether 102 inside the buoy 104. The illustratedembodiment includes the tether 102, the buoy 104, a tether entry point106, magnetostrictive elements 108, free connection points 110, andsecured connection points 112. In the illustrated embodiment, the tether102 passes into the internal region of the buoy 104 through the sealedentry point 106. In some embodiments, the sealed entry point 106includes a seal to allow the tether 102 to move without allowing waterto enter the buoy 104. In the illustrated embodiment, the individualmagnetostrictive generators or elements 108 are disposed along aninternal continuation of the tether 102 inside the buoy 104. In oneembodiment, the buoy 104 contains the same amount of magnetostrictivecomponents 108 as would normally be deployed along the length of thetether 102 with the elements 108 deployed along the length of the tether102 outside of the buoy 104. This also affords the opportunity ofincreasing the load through use of levers, pulleys, block-and-tackle,hydraulic systems or other force multiplication systems (illustrated byexamples 114) that may be attached at connection points 110 and 112.These systems trade distance for force, so their use would allow thebuoy 104 to move more than it would were they not used. This may reducethe strain on the tether 102 and the system 100 as a whole. In someembodiments, the free connection points 110 allow the portion of thetether 110 internal to the buoy 104 to roll through and apply strain toeach of the elements 108. In some embodiments, the free connectionpoints 110 may allow for force modification through use of hydraulic,electric, magnetic, or mechanical force modifiers as described above. Inthe illustrated embodiment, the tether 102 attaches the buoy 104 to theseabed. In another embodiment, the tether 102 attaches the buoy 104 to aheave plate (not shown) or a fixed sub-surface structure to allow thebuoy 104 to move with the ocean waves and create stress in the elements108.

FIG. 2 depicts one embodiment of a buoy-housed system 120 with an upperload plate 122. In the illustrated embodiment, the load to themagnetostrictive generators or elements 108 is compressive. In oneembodiment, the buoy 104 houses one or more individual magnetostrictivegenerators or elements 108 that are mechanically in series or parallel(i.e. sharing an applied load, or carrying the same applied load),deployed between an upper load plate 122 which is connected to thetethers 102, and an internal surface of the buoy 104. This system wouldgreatly reduce or eliminate the need for precompression of themagnetostrictive rods 108 because the hydrodynamic forces would resultin compression rather than tension. This may provide substantial costsavings by eliminating the need for components used for pre-compression.In one embodiment, the tether 102 may be run through a pulley or otherdevice at the top of inside of the buoy 104 with the load plate 122 hungtowards the bottom of the buoy 104 and the elements 108 hung from theupper interior surface of the buoy 104. This would allow the weight ofthe load plate 122 to apply tension to the elements 108 when the tether102 is relaxed and compression when the tether 102 is pulled taught bythe movement of the ocean waves. Other embodiments may include fewer ormore arrangements and components to incorporate less or morefunctionality.

The illustrated system also benefits from the location of themagnetostrictive generators as included inside the buoy and separatedfrom the water. Each unit does not require a separate casing and indeedmay have completely different architecture and geometry relative to thearchitecture and geometry of PTOs disposed on the tethers. Indeed, theload can be transferred to one or more magnetostrictive alloy components108 (rods, bars etc) with none of the external casing, pre-compressionand other components associated with other systems which incorporatemagnetostrictive PTOs. In another embodiment, a single, bottom-foundedhousing (not shown) would have many of the same benefits. Theconfiguration could be similar to any buoy-housed configuration, as thebottom-founded concept is essentially an upside-down version of the buoyhousing disposed at the bottom of the tethers. This configuration couldbe advantageous in that the direction of loading could be reversedthrough a pulley, gear of alternative system, which, in combination withthe bottom founding, could simplify the structural requirements of theenclosure. The bottom-founded system would also avoid an increase inbuoy size that might be necessary in the buoy-housed configuration inorder to meet the buoyancy requirements related to survivability. Thisconfiguration would also eliminate the need for the electricalumbilicals that would run from the buoy to the ocean floor in either thebuoy-housed or individual PTO enclosure configuration, which couldincrease the reliability of the system.

In a recent patent application we disclosed the use of a heave plate asan advantageous design for a mooring system (see Provisional ApplicationNo. 61/664,444, filed Jun. 26, 2012, entitled “Magnetostrictive WaveEnergy Harvester with Heave Plate”). With that disclosure incorporatedby reference herein it is also possible that a bottom-founded designcould mount the PTO units within a structure that serves as the heaveplate. One advantage to this configuration is that the sealed containerthat houses the PTO units would have a lower sealing pressurerequirement because in general a heave plate is deployed a shortdistance below the water surface as opposed to being located on the seafloor.

Additionally, the use of hydraulics can create advantages in theharvesting of energy from this system. In one embodiment, the force onthe tethers 102 causes a piston (described in greater detail withreference to FIGS. 4( a) and 4(b)) to compress a fluid such as hydraulicoil. The energy stored in the pressurized fluid can then be used toapply stress to the magnetostrictive elements housed in the buoy.Through the use of valves, the energy can be released at a controlledfrequency over a controlled amount of time. This could be advantageousfor power production. Another use of the hydraulic energy would be tomove a piston of a different bore size to obtain a forceamplification/reduction which could be applied to the magnetostrictiveelements. Another benefit to the use of the hydraulic energy would be toprevent extreme loads caused by large waves to be applied to the systemthrough controlled release systems. This could be done by using a valveto release the pressure over a certain value (describe in more detailbelow with reference to FIG. 4( a)). Another embodiment includes adouble acting hydraulic cylinder to compress hydraulic fluid on bothsides of the wave. Other embodiments may incorporate other components toachieve more or less functionality. Some example of alternativeembodiments are illustrated in FIGS. 2( b) and 2(c).

FIG. 4( a) depicts a schematic diagram of one embodiment of a hydraulicforce modifier system 500. The illustrated embodiment includes a smallarea hydraulic piston 502, a hydraulic reservoir 504, hydraulic fluid506, a large area hydraulic piston 508, a magnetostrictive rod element510, and a coil 512. In one embodiment, the small area hydraulic piston502 has a hydraulic surface with a small area. In one embodiment, thesmall area hydraulic piston 502 receives an input load from an externalsource of mechanical movement. The small piston 502 moves into and outof the hydraulic reservoir to apply force to the hydraulic fluid 506. Asthe small piston 502 applies force to the hydraulic fluid 506, the largearea hydraulic piston 508 is acted upon by the hydraulic fluid in aneffort to reach equilibrium. If the small piston 502 moves into thehydraulic reservoir 504, the hydraulic fluid 506 would be pressurizedand apply a force to the large piston 508. The large piston 508 wouldthem move out of the hydraulic reservoir 504 and apply a force to themagnetostrictive element 510. The force on the magnetostrictive element510 would cause mechanical strain in the element 510. The resultingstrain would cause a change in the magnetic field of the element 510.The change in the magnetic field of the element 510 would generateelectrical power in the coil 512 surrounding the element 510 throughinduction. The illustrated system 500 allows a relatively larger traveldistance of the small piston 502 to result in a relatively smallertravel distance of the large piston 508. In some embodiments, themodification of the force placed on the small piston 502 by the loadapplies a more suitable force on the magnetostrictive element 510. Thisallows for more efficient power generation and increased durability ofthe system 500 over conventional systems.

In another embodiment, the small piston 502 and the large piston 508 arereversed. This orientation would allow for a load with a small traveldistance to apply a larger travel to the magnetostrictive element 510.FIG. 4( b) depicts another embodiment of the hydraulic force modifiersystem 500 of FIG. 4( a). In the illustrated embodiment, the load isapplied to the small piston 502 which pressurizes a storage vessel 514to store the energy applied by the load. The storage vessel 514 releasesthe energy through a valve 516 to the large piston 508 to apply force tothe element 510. In some embodiments, the energy is released at aspecific frequency to increase the efficiency of the power generation.In some embodiments, the pistons 502 and 508 are swapped. In someembodiments, the reservoir 506 is divided (shown by the dashed linethrough reservoir 506) to isolate the force from/to each piston 502 and508. Other embodiments may include other arrangements with fewer or morecomponents to achieve less or more functionality.

Other embodiments may incorporate one or more other aspects from relateddescriptions, including the subject matter described and shown in U.S.application Ser. No. 12/603,138, filed on Oct. 21, 2009, and entitled“Method and Device for Harvesting Energy from Ocean Waves,” U.S.application Ser. No. 13/016,828, filed on Jan. 28, 2011, and entitled“Wave Energy Harvester with Improved Performance,” U.S. application Ser.No. 13/016,895, filed on Jan. 28, 2011, and entitled “Apparatus forHarvesting Electrical Power from Mechanical Energy,” U.S. applicationSer. No. 13/361,806 filed on Jan. 30, 2012, and entitled “EnergyHarvesting Methods and Devices, and Applications Thereof,” U.S.Provisional Application No. 61/664,444, filed on Jun. 26, 2012, andentitled “Magnetostrictive Wave Energy Harvester with Heave Plate,” U.S.Provisional Application No. 61/668,280, filed on Jul. 5, 2012, andentitled “Power Generation MWD/LWD Tools and Telemetry,” U.S.Provisional Application No. 61/674,982, filed on Jul. 24, 2012, andentitled “Method and Device for Downhole Power Generation,” and U.S.Provisional Application No. 61/738,757, filed on Dec. 18, 2012, andentitled “Downhole Energy Harvesting Method and Device each of which isincorporated herein in its entirety.

In the above description, specific details of various embodiments areprovided. However, some embodiments may be practiced with less than allof these specific details. In other instances, certain methods,procedures, components, structures, and/or functions are described in nomore detail than to enable the various embodiments of the invention, forthe sake of brevity and clarity.

Although the operations of the method(s) herein are shown and describedin a particular order, the order of the operations of each method may bealtered so that certain operations may be performed in an inverse orderor so that certain operations may be performed, at least in part,concurrently with other operations. In another embodiment, instructionsor sub-operations of distinct operations may be implemented in anintermittent and/or alternating manner.

Although specific embodiments of the invention have been described andillustrated, the invention is not to be limited to the specific forms orarrangements of parts so described and illustrated. The scope of theinvention is to be defined by the claims appended hereto and theirequivalents.

What is claimed is:
 1. A device for generating electrical energy frommechanical motion, the device comprising: at least one magnetostrictiveelement; and at least one force modifier mechanically coupled to themagnetostrictive element, the force modifier to receive an input forceand apply a modified force to the magnetostrictive element.
 2. Thedevice of claim 1, wherein the force modifier comprises a mechanicalsystem.
 3. The device of claim 2, wherein the mechanical systemcomprises a lever.
 4. The device of claim 2, wherein the mechanicalsystem comprises a pulley.
 5. The device of claim 2, wherein themechanical system comprises a block-and-tackle system.
 6. The device ofclaim 1, wherein the force modifier comprises a hydraulic system.
 7. Thedevice of claim 1, wherein the modified force applied to themagnetostrictive element is greater in magnitude than the input force.8. The device of claim 1, wherein the modified force applied to themagnetostrictive element comprises a compressive force and the inputforce comprises a tensile force.
 9. The device of claim 6, wherein thehydraulic system comprises a first hydraulic piston having a first areaand a second hydraulic piston having a second area, wherein the firstarea and the second area are not equal.
 10. A method for generatingelectrical energy from mechanical motion, the method comprising:receiving an input force from a mechanical motion; modifying the inputforce; and applying a modified output force to a magnetostrictiveelement.
 11. The method of claim 10, wherein modifying the input forcefurther comprises operating a mechanical system.
 12. The method of claim11, wherein the mechanical system comprises at least one of a list ofsystems, the list comprising: a lever; a pulley; and a block-and-tackle.13. The method of claim 10, wherein modifying the input force furthercomprises operating a hydraulic system.
 14. The method of claim 10,wherein modifying the input force comprises transforming a tensile inputforce to a compressive output force.
 15. The method of claim 13, whereinthe hydraulic system comprises a first hydraulic piston having a firstarea and a second hydraulic piston having a second area, wherein thefirst area and the second area are not equal.
 16. A buoy apparatus forgenerating electrical energy from motion of ocean waves, the devicecomprising: a buoy housing; a magnetostrictive element disposed withinan interior of the buoy housing; a tether coupling point; a forcemodifier disposed at least partially within the interior of the buoyhousing and coupled to the tether coupling point, the force modifier toreceive an input force from the tether coupling point and apply amodified output force to the magnetostrictive element; and a coildisposed within a magnetic field of the magnetostrictive element. 17.The apparatus of claim 16, wherein the force modifier is configured toapply a compressive force to at least one magnetostrictive element whilethe input force is tensile in nature.
 18. The apparatus of claim 16,wherein the force modifier comprises a hydraulic system.
 19. Theapparatus of claim 18, wherein the hydraulic system comprises a firsthydraulic piston having a first area and a second hydraulic pistonhaving a second area, wherein the first area and the second area are notequal.